7-2014_biofuel_gressel_levy_10.ppt

Cahen, Erice 7-2014 (J. Gressel)
The Challenges for Biofuels
Maybe; likely a
high %, for a while
Maybe by using
algae, waste or
marginal land ?
Lower than just fossil
fuel;more sustainable
1- Food vs.Fuel dilemma
2- Can we produce
the amounts needed?
3- Environmental impact
4- EROI Try to be honest
Jonathan Gressel
Avi Levy &
Biofuel consortium
Dept. of Plant Sciences

Outline
•Zero Generation Biofuels
•First Generation Biofuels
The problems – food vs. fuel
•Second Generation Biofuels
- Lignocellulosics for ethanol
- Oils for biodiesel
•Future

Plant photosynthesis
is < (<<) 1% efficient
Photosynthetic
MICRO-organisms
can do better, ~ 4%
The source of all biomass

Traditional biofuels
India
Africa
Inefficient
Polluting
Environmentally
negative
Can we do better?

OATS was traditional biofuel in
temperate climate areas
Cultivated on ca. 20% of land

Oats fueled all of farming:
mules, horses and laborers

Outline
and the problem – food vs. fuel
•Future

Ethanol: an increasing portion of the US maize crop

Monthly production and net imports of fuel ethanol in the U.S. 1993-2012. Data from EIA

What are world implications?
Biofuels: Good News/Bad News to developing world
Bad news: no more cheap/free grain for food
security in time of famine
Good news: No more “dumping” subsidized grain,
sold
below production costs
Developing world farmers can now compete
and easily triple yields

Biofuels: Good News/Bad News to developed
world farmers
Good news to grain farmers - prices stable
Bad news to dairy/beef/chicken/hog farmers
- grain prices high…
Bad news to consumers –
do not lower fuel prices, higher food costs

Ethical question Europe (Japan) must ask:
Is it right to support eliminating rainforests
and jungles elsewhere, for Europe (Japan) to
import soy/palm oil for biodiesel so that
Europe (Japan) can preserve “Landscapes”?
Ethical question all must ask:
Is it ethical to drive a big car on biofuel,
considering effect on agriculture ?

Is there energy gain for maize (corn)  grain ethanol?
(LUC)

All depends on how we do the calculations
Most calculations do not include:
- accounting of byproducts
- recent advances
- appropriate “systems boundaries”
Dale does calculations, based on ability to
replace petroleum or on greenhouse gases
produced per km driven;
Pimentel & Patzek strongly disagree
(you can do the math yourself, using the student ppt* on it)
* See Total Energy Analysis of ethanol production from corn
on http://wws.weizmann.ac.il/AERI/presentations

Teosinte-
the
progenitor
Corn ca. 1492
Hybrid
corn
Domestication of corn

David McKay SEWTHA
Comparing Potential Biofuel Crops
Power Density [W / m2 ] (cf. to Si solar panel in Kalahari desert ~ 25 Wc / m2 )

The Economist 2009
Comparing Potential Biofuel Crops

Calculated from Chisti, Biotech. Adv. 25:294-306, 2007
Area needed to replace 15% of USA transport fuels*
Crop Oil
yield
(l/ha)
area
needed
(M ha)
% of
existing
arable area
Maize 170 460 180
Soybean 445 180 65
Oilseed rape 1,190 65 40
Jatropha 1,890 40 15
Oil palm 5,950 15 7.2
Algae/cyanobacteria
a
59,000 1.3 1.3
Algae/cyanobacteria
b
137,000 0.6 0.6
a
containing 30% oil b
containing 70% oil
* EtOH provides ~ 1 % (2012)

15
Land Use to Ethanol
-
20.00
40.00
60.00
80.00
100.00
120.00
140.00
160.00
Current ethanol production
(Brazil + USA)
Replacement of 10% total
gasoline consumption
Replacement of 10% total
crude oil consumption
World's Agriculture Area
31 million hectares
123 million hectares
1 billion hectares
7.4 million hectares
J. Goldemberg, SP
Brazil: 50% of sugar cane crop
 > 40% of non-diesel fuel
13.6 million (2011)

Sugar Cane Ethanol Production in Brazil
Fonte: NIPE-Unicamp, IBGE e CTC.
In about 3 million hectares (1% of
country’s arable lands), Brazil
produces ethanol enough to replace
50% of national gasoline
consumption.
25 million hectares of
degraded pasturelands are
available
87% of cane
production
J. Goldemberg, SP

First generation
not sustainable in medium term

Outline
use agricultural wastes lignocellulosics
- Grasses
but… such crops were not domesticated for biofuels!
•Future (3d generation)

How are plants built ?
HOW ARE
PLANTS
BUILT?

© Materials Research Society 2012
Fig25_05
HOW ARE
PLANTS
BUILT?

The plant cell wall is built of
Cellulose, hemicellulose and lignin—the most abundant
polymers on the planet—sources of sugars for fermentation

Can grasses++ be turned into fuel?

Switchgrass does not defy the law of
conservation of matter; it grows best with …
water nitrogen fertilizer
Data of Lee et al. and Muir et al, collated in Gressel,
“Genetic Glass Ceilings, Hopkins, 2007

The non-degraded switchgrass residue is
burnt  energy for process
Contains 5-10% ash, > 60% of ash (=silica)
On burning releases 50% more non-precipitable
silica than coal*
Same with sugarcane bagasse/other grasses
Rice has highest silica content of grasses
How dangerous is burning rice straw?
*Blevins, L.G., and Cauley, T.H. (2005) Fine particulate formation during
switchgrass/coal co-firing. Journal of Engineering for Gas Turbines and Power-
Transactions of the ASME 127, 457-463

Silicon not a required element for plants
small amounts may be useful
but not the high amounts in many grasses,
including sugarcane
Silicon transporters being discovered in plants
use antisense RNA or RNA-interference to
lower their levels?

Process:
Heat + acid pre-treatment (delignification)
Enzymatically digest cellulose to sugars
Ferment sugars to ethanol
But half of cellulose is unavailable
208 kg ethanol/tonne straw
Claim: with present technology - Canadian
wheat straw could provide ethanol for almost
all Canadian automobiles; maybe, but …

Cellulosic
ethanol Acid, Heat
Is this environmentally sound?

Can less heat/less acid be used if grass is
modified?

Lignin
Less lignin should 
higher grain yield
Despite common
suggestions / myth:
no direct correlation
between lignin and
strength

The higher the lignin content
the lower the digestibility

Solution:
Modify crop
for:
- less lignin
or
- modified lignin
or
- more cellulose
Should reduce the
acid/heat
requirement,
add to yield

Wheat straw as feedstock for biofuel
• Abundant ~ 0.7 GTonne/year
• Cheap
• Does not compete with food
• 1 GT could provide 10s % USA fuel/yr?

World grain production (»straw production) [MTonne]
wheat rice maize sorghum millet
million metric tons
568 579 602 55 26
Total grain (total straw) »2,000 million tonne
Source: FAO statistics – 2004
Why not use 2 GTonne of free waste biomass ?
With switchgrass and miscanthus, land must
be bought, dedicated to cultivation, watered,
fertilized and harvested.
Straw is available “free” - a by-product of
grain production

Straw has –ve economic/environmental value
- harbors pathogens if not burnt
- requires fungicides on next crop
- releases CO2 when burnt
- binds nutrients while biodegrading
 requires more fertilizer - pollution
-Despite being ~ 70% carbohydrate,
straw has relatively low value
- as animal feed (less than half digested)
or - as bioethanol source.

Is using straw waste sustainable?
Soil scientists used to say “no!”
because need organic matter in soil
(but straw used to be burnt in Europe)
Most now agree – OK, if 20% left in field

Outline
use agricultural wastes lignocellulosics
- Grasses
•Future (3d generation)
Cultivate & use biofuel-dedicated crops
- perennial lignocellulosics
- perennial oilseeds
- ALGAE
but ….. first learn from what we are doing now

Oilseed rape is favored for temperate climes
Is it nice to the environment?
Worldwide, oilseed rape emits ca. 9000 Tonnes
Before the ban Europe consumed 18,000 T CH3Br
Is “natural” CH3Br OK, but synthetic bad?
Is it OK to double the area for biofuel?
*Gan, J., et al. (1998) Production of methyl bromide by terrestrial higher plants.
Geophysical Research Letters 25, 3595-3598

Palm oil  poor biodiesel (by transesterification*)
congeals at low temperatures
Must catalytically crack it - or mix
Needs shorter chain length
- antisense elongases
Needs more mono un-saturation
- engineer desaturases
Such engineering
 in non-cholesterogenic “palmolive” oil
*

Only by bringing genes from
elsewhere can we breach the
glass ceilings

LIPIDS
fatty acid chains
Cutins - polymers of short fatty
acids; these are unique to plants
Triglycerides - three fatty acid
chains bound to a single molecule
of glycerol
Waxes - polymers of long
fatty acids
Triglycerides

Biodiesel from various sources

30% oil - seeds get US$140/ton (optimistic)
- fruits hand-harvested
- fruits dried in the shade
- seeds removed by hand
Is Jatropha
real or gimmick
(keep the poor
poor)?

Some more info on Jatropha curcas
common plant names: Black vomit nut, Purge nut, etc.
common oil names: hell oil, oleum infernale, etc.
Toxins: Curcin (a toxalbumin) - similar to ricin
Phorbol esters - diterpenoids (alkaloids)
skin tumor promoters
No antidote known
See: http://www.inchem.org/documents/pims/plant/jcurc.htm
Jatropha poisoning resembling organophosphate intoxication
Clin. Tox. 44 337,2006
Imagine releasing a transgenic crop with such
components….
So, what to do with toxic byproducts?

Websites: “curcin is heat-degradable”
Reference:“degradable by prolonged autoclaving”
Curcin ~ Ricin
potent toxin
(slow death marked by vomiting &diarrhea)

Castor has similar problems as Jatropha
Seeds contain 0.2 to 3% ricin
1 mg/kg toxic
fill car with 50 liters (13 gallons diesel)
enough ricin by-product to kill 3 people
at lowest content, 45 at highest
Ricin protein “easy” to eliminate
transgenically!

Oklahoma bill against castor production & transportation
proposed. Why?
Castor beans contain 50% or more oil for
producing biofuels.
They also contain high levels of ricin.
Edible crop producers became concerned about
ricin residues in fields, equipment, storage
bins, and transportion.
Jatropha banned in Western Australia
as “toxic to man and livestock”
Approach should be to ban the toxins – and
stimulate DOMESTICATION

- Short term – biofuels from food crops
- Medium term –
biofuels from cellulosic wastes & algae
-Long term - … algae ??
and, very likely, successful biofuel
feedstocks will be transgenic

Seambiotic (ω3),
Transalgae (fishmeal)
Nature Beta Technol. (β-carotene)

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